Organosilicate materials with mesoscopic structures

ABSTRACT

Template-based methods fabricate organosilicate materials with mesoscopic structures. The methods include providing solutions of amphiphilic template molecules, mixing amphiphilic organosilicate precursors into the solutions to form mixtures, and evaporating solvent from the mixtures. The evaporation steps produce composites in which the amphiphilic organosilicate precursors have nontrivial mesoscopic structures.

BACKGROUND

[0001] 1. Field of the Invention

[0002] This invention relates to organosilicate materials.

[0003] 2. Description of the Related Art

[0004] Some techniques use structured phases of amphiphilic blockcopolymer molecules as templates for fabricating polymeric materialswith mesoscopic structures. The block copolymer molecules self-assembleinto stable structures with mesoscopic structures when theirconcentrations and temperatures are in specific ranges. Since blockcopolymer molecules have phases with different types of mesoscopicstructure, these template-based techniques have been used to fabricatepolymeric materials with a variety of types of mesoscopic structures.

[0005] Typical template-based methods involve several fabrication steps.The methods include making a starting solution that contains both blockcopolymer molecules and monomers for making the desired material. In thestarting solution is a uniform solution of the two types of molecules.The methods include evaporating solvent from the starting solution untilthe concentration of block copolymer molecules achieves a concentrationfor which the stable phase for block copolymer molecules has anontrivial mesoscopic structure. At this concentration, the blockcopolymer molecules self-assembly into the nontrivial structure.Self-assembly by the block copolymer molecules causes the monomers,which are intermixed with the block copolymer molecules, to alsocondense into a similar or different mesoscopic structure. The methodsinclude heating the material with the mesoscopic structure to polymerizethe monomers into a solid whose structure is fixed by the condensation.

[0006] The template-based methods have used alkoxide monomers tofabricate polymeric materials with a variety of morphologies. Thesemorphologies include spherical, cylindrical, lamellae, and gyroidstructures. But, the alkoxide precursors typically produce polymericmaterials wettable by water.

SUMMARY

[0007] Various embodiments of template-based methods fabricateorganosilicite materials with mesoscopic structures from precursorshaving hydrophobic moieties The hydrophobic moieties can cause changesto affinities towards water during curing, e.g., due to shedding ofreactive hydrophilic moieties. Such changes can destroy template-inducedstructures, which are based on interactions between hydrophilic andhydrophobic moieties. The affinity changes can cause precursors to phaseseparate so that the previously produced mesoscopic structures aredestroyed. Curing-induced phase separations have impeded the successfuluse of alkoxide precursors having hydrophobic moieties in the productionof materials with mesoscopic structures.

[0008] Various embodiments eliminated curing-induced destruction ofmesoscopic structures by using precursors that remain amphiphilic duringcuring. In particular. the precursors include both hydrophobic andhydrophilic moieties, and the respective hydrophobic and hydrophiliccharacters of these moieties are unchanged by the curing reactions thatcrosslink composites. Thus, crosslinking does not cause drastic changesin molecular affinities of the organosilicate precursors.

[0009] One embodiment features a template-based method for fabricatingan organosilicate material with a mesoscopic structure. The methodincludes providing a solution of an amphiphilic template molecules,mixing amphiphilic organosilicate precursors into the solution to form amixture, and evaporating solvent from the mixture. The evaporationproduces a composite in which the amphiphilic organosilicate precursorshave a nontrivial mesoscopic structure.

[0010] Another embodiment features a solid that includes crosslinkedamphiphilic organosilicate precursors. The amphiphilic organosilicateprecursors form a matrix with an array of micro-structures dispersed inthe matrix.

BRIEF DESCRIPIION OF THE DRAWINGS

[0011]FIG. 1A is a cross-sectional view of a composite with an orderedarray of cylindrical micro-structures therein;

[0012]FIG. 1B is a cross-sectional view of another composite with anordered array of cylindrical micro-structures therein;

[0013]FIG. 1C is a cross-sectional view of another composite with anordered array of lamellar micro-structures therein;

[0014]FIG. 2 is a flow chart illustrating a method for fabricating anorganosilicate solid with a nontrivial mesoscopic structure;

[0015]FIG. 3 is a flow chart illustrating a specific embodiment of themethod of FIG. 2 that is based on a sol-gel reaction;

[0016]FIG. 4 shows an amphiphilic organosilicate molecule producedduring prehydrolysis of a sol-gel material used in the method of FIG. 3;

[0017]FIG. 5 shows an organosilicate molecule produced by crosslinkingtwo of the molecules of FIG. 4;

[0018]FIG. 6 illustrates the form of an organosilicate precursor made byfurther crosslinking molecules of FIG. 5 during prehydrolysis of asol-gel material; and

[0019]FIG. 7 is cross-sectional view of a planar waveguide that uses aporous organosilicate material produced by the method of FIG. 3.

DETAILED DESCRIPITION OF EMBODIMENTS

[0020] Herein precursors are monomers or oligomers that can becrosslinked or polymerized.

[0021] Various embodiments use inhomogeneous phases of templatemolecules to produce organosilicate materials with nontrivial mesoscopicstructures. Self-assembly of the template molecules into nontrivialmesoscopic structures causes amphiphilic organosilicate precursors toarrange themselves in similar structures due to strong interactionsbetween various portions of the two types of molecules. In particular,interactions cause either hydrophilic or hydrophobic portions of the twotypes of molecules to assemble themselves in adjacent or overlappingphysical regions.

[0022] The various embodiments avoid destruction of template-inducedstructure by using organosilicate precursors whose hydrophilicaffinities are stable to curing. In particular, the organosilicateprecursors are amphiphilic both before and after curing. Thus, curingdoes not produce drastic changes in affinities of organosilicatemolecules for water. Such drastic changes in affinities could otherwisesignificantly physical rearrange the precursors thereby causing a lossof mesoscopic structure during curing.

[0023] Some of the embodiments of template-based fabrication methodsproduce organosilicate materials that are not hydrophilic. In thesematerials, the presence of hydrophobic moieties causes the materials tobe resistant to absorption of water. In some of the materials,hydrophobic moieties of the original organosilicate precursors areconcentrated on external surfaces thereby making the materialsnon-wettable by water.-

[0024] Structures of several organosilicate composites with nontrivialmesoscopic structures are illustrated in the cross-sectional views ofFIGS. 1A-1C. A composite or solid with a nontrivial mesoscopic structurehas an array of micro-structures dispersed therein. Exemplarymicro-structures include cylindrical, gyroid, lamellar, orspherical-type structures. In composites and materials with suchstructures. typical diameters of cylindrical or spherical-typemicro-structures, thicknesses of lamellar micro-structures, and intermicro-structure distances are typically in a range of about 2 nanometers(nm) to about 200 nm.

[0025]FIG. 1A shows a composite 2 of amphiphilic organosilicateprecursors and amphiphilic template molecules, e.g., surfactants orblock copolymers. The composite 2 includes an array of cylindricalmicro-structures 3 dispersed in a matrix 4. The micro-structures 3 havethe same diameter, e.g., about 2-200 nm, and include outer annularregions 5, inner annular regions 6, and cores 7. The outer annularregions 5 and matrix 4 contain respective hydrophobic portions andhydrophilic portions of the organosilicate precursors. The inner annularregions 6 and cores 7 contain respective hydrophilic blocks andhydrophobic blocks of the template molecules and function as a template.The hydrophilic portions of organosilicate precursors and templatemolecules are physically adjacent, because this physical arrangementleads to a lower free energy under the temperature and concentrationconditions for the composite 2.

[0026]FIG. 1B shows another composite 8 of amphiphilic organosilicateprecursors and amphiphilic template molecules, e.g., surfactants orblock copolymers. The composite 8 includes a uniform array ofcylindrical micro-structures 9 dispersed in a matrix 10. The cylindricalmicro-structures 9 include annular regions 11 and cores 12. The annularregions 11 contain a uniform material containing hydrophilic portions ofboth the organosilicate precursors and the template molecules. The cores12 contain hydrophobic portions of the template molecules. The matrix 10contains hydrophobic portions of the organosilicate precursors.Hydrophilic portions of the organosilicate precursors and the templatemolecules intermingle in the same physical region, because this physicalarrangement leads to a lower free energy under the temperature andconcentration conditions for making the composite 8.

[0027] Other composites and solids of amphiphilic organosilicateprecursors and amphiphilic template molecules (not shown) have uniformor random arrays of spherical-type micro-structures. The morphologies ofthese arrays of micro-structures have the forms already shown for thearrays of cylindrical micro-structures 3, 9 in the cross-sectional viewsof the composites 2, 8 of FIGS. 1A and 1B.

[0028]FIG. 1C shows a portion of an organosilicate composite 14 thatincludes an array of lamellae 15-18. The lamellae 15 and 16 containrespective hydrophilic and hydrophobic bocks of amphiphilicorganosilicate precursors. The lamellae 17 and 18 contain respectivehydrophobic and hydrophilic blocks of amphiphilic template molecules,e.g., block copolymers. In the composite 14, hydrophilic portions oforganosilicate precursors and template molecules occupy physicallyadjacent lamellae 15, 18, and hydrophilic portions of organosilicateprecursors and copolymer molecules occupy physically adjacent lamellae16, 17. In other embodiments (not shown), either hydrophobic portions orhydrophilic portions of both types of molecules intermix in the samelamellae.

[0029]FIG. 2 illustrates a method 20 for constructing an organosilicatematerial with a mesoscopic structure from a homogeneous solutioncontaining amphiphilic template molecules. Herein, template moleculesare molecules that tend to self-assemble into composites with nontrivialphysical mesoscopic structures under certain conditions, e.g.,concentration and temperature. Exemplary template molecules includesmall molecule surfactants and block copolymers. The type of mesoscopicstructure formed by such molecules depends on the type of templatemolecules. The molecular concentration of the molecules, and/or thetemperature.

[0030] The method 20 includes preparing a starting solution of theamphiphilic template molecules (step 22). The concentration andtemperature of the starting solution is typically selected to produce ahomogeneous solution of the template molecules, i.e., in a phase withouta mesoscopic structure.

[0031] Method 20 also includes providing a second solution ofamphiphilic organosilicate monomers or organosilicate oligomers capableof being crosslinked (step 24). The organosilicate precursors havefunctional groups supporting crosslinking reactions. The organosilicateprecursors also have both hydrophobic moieties and hydrophilic moietiesthat maintain their respective hydrophilic and hydrophobic natures underconditions of the crosslinking reactions. Exemplary organosilicateprecursors are already partially crosslinked to produce amphiphilicmolecules of desired molecular weights.

[0032] Method 20 also includes mixing the two solutions to form a newsolution that contains both the amphiphilic organosilicate precursorsand the template molecules (step 26). The new solution is a homogeneoussolution and typically does not have mesoscopic structure under themixing conditions.

[0033] Method 20 includes evaporating solvent from the new solution,i.e., containing both the template molecules and organosilicateprecursors and thereby causing the formation of a composite with anontrivial mesoscopic structure (step 28). To produce the evaporation,the solution is heated. The evaporation causes a phase with a mesoscopicstructure to become more stable than the phase in which the templatemolecules are homogeneously distributed in the solvent. Thus, theevaporation causes the amphiphilic template molecules physicallycondense or self-assemble into a composite with the nontrivialmesoscopic structure.

[0034] In the nontrivial mesoscopic structure, hydrophobic andhydrophilic blocks of the template molecules are distributed in separatephysical regions. This physical separation of the hydrophobic andhydrophilic portions of the amphiphilic template molecules induces asimilar physical self-assembly of the amphiphilic organosilicateprecursors. The self-assemble produces a composite of both theorganosilicate precursors and the template molecules, e.g., composites2, 8, 14 of FIGS. 1A, 1B, or 1C. In these composites, either thehydrophilic or the hydrophobic portions of both the organosilicateprecursors and template molecules are concentrated in physicallyneighboring or overlapping regions. The hydrophilic portions of bothtypes of molecules occupy separate physical regions than the hydrophobicportions of these molecules.

[0035] Method 20 also includes curing the physical composite, which hasa nontrivial mesoscopic structure, to form a crosslinked solid (step30). Curing results from heating or irradiating the composite tostimulate chemical reactions among functional groups on theorganosilicate precursors. These reactions produce chemical crosslinks,i.e., bonds, between the organosilicate precursors and cause theprecursors to lose hydrophilic moieties. During curing, organosilicateprecursors remain amphiphilic. because the precursors have bothhydrophobic moieties and hydrophilic moieties that are either unreactiveunder the reaction conditions or react without changing their affinitiesfor water. Thus, curing does not cause drastic changes to affinities ofthe organosilicate precursors for water. For example, curing does notchange the precursors from hydrophilic or amphiphilic molecules intohydrophobic molecules.

[0036] Eliminating drastic changes in affinities of the organosilicateprecursors for water is important to maintaining the template-inducedmesoscopic structure as curing progresses. Other attempts to fabricatehydrophobic materials with mesoscopic structures from precursors withalkoxide functional groups failed, because the precursors changed fromamphiphilic to hydrophobic during curing. Prior to curing hydrophilicportions of those precursors were physically neighboring to orintermixed with hydrophilic regions of the template in composites whoseorganosilicate components had nontrivial mesoscopic structures, e.g., asshown in FIGS. 1A, 1B, and 1C. Nevertheless, the organosilicateprecursors rearranged themselves as curing progressed due to theirdrastic affinity changes. As the organosilicate precursors becamehydrophobic during curing their original physical positions nearhydrophilic regions of the template molecules became unstable. Thiscaused the organosilicate precursors to rearrange and destroyed thetemplate-produced structure, i.e., producing a crosslinked solid withouta mesoscopic structure.

[0037] Referring again to FIG. 2, method 20 also includes performing achemical treatment on the crosslinked solid produced at step 30 toremove part or all of the block copolymer template molecules (step 32).Exemplary chemical treatments include: burning or dissolving templatemolecules out of the solid, using ozonolysis to break backbones of thetemplate molecules thereby releasing the constituents from the solid, orusing an O₂ plasma reactive ion etch (RE) to remove template molecules.

[0038] Removing the template molecules produces a porous organosilicatesolid. FIG. 3 illustrates a particular method 40 for makingorganosilicate materials according to method 20 of FIG. 2. In the method40, the template molecules are the block copolymer moleculespoly(butadiene)_(n)-b-poly(ethylene oxide)_(m) (PBu-b-PEO).

[0039] In PBu-b-PEO, the poly(butadiene)_(n) block and poly(ethyleneoxide)_(m) block are the respective hydrophobic and hydrophilic blocksof the amphiphilic block copolymer. The integers n and m, whichcharacterize the chain length of these blocks and have values of about10-20,000 and preferably have values of about 50-1,000. Varying thevalues of n and m enable making templates for different mesoscopicstructures.

[0040] The method 40 includes preparing a starting solution of theamphiphilic block copolymer PBu-b-PEO (step 42). The starting solutionincludes about 5 weight % PBu-b-PEO in a solvent that is an approximate50/50 volume % mixture of chloroform and tetrahydrofuran. The 50/50volume % solvent mixture both dissolves the block copolymer moleculesand produces a solvent compatible with prehydrolyzed sol-gel material,i.e.. a prehydrolyzed sol-gel mater dissolves into this solvent mixture.The starting solution is homogenous at the above starting weightconcentration and room temperature.

[0041] The method 40 also includes preparing an aqueous solution of aprehydrolyzed sol-gel material, i.e., a solution of organosilicateprecursors (step 44). The sol-gel material is itself formed by reactingtwo silicate alkoxide monomers. One monomer is (CH₃)Si(OCH₂CH₃)₃(MTEOS), which has a hydrophobic CH₃ moiety. The other monomer is(CH₃O)₃Si(CH₂)₃OCH₂(CHCH₂O) (GLYMO), which has the hydrophilic moiety,(CH₂)₃OCH₂(CHCH₂O). The hydrophobic moiety, CH₃, and hydrophilic moiety,(CH₂)₃OCH₂(CHCH₂O), do not react during prehydrolysis of the sol-gelmaterial and do not change their respective hydrophobic and hydrophilicnatures during subsequent curing.

[0042] Other embodiments use different silicate alkoxide silicates toprepare the solgel material. Alternate silicate alkoxides for themonomer with a hydrophobic moiety include methyltriethoxysilane,phenyltriethoxysilane, n-octyltriethoxysilane, andtridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane. Alternate silicatealkoxides for the monomer with a hydrophilic moiety include3-glycidoxypropyltrimethoxysilane. mercaptopropyltrimethoxysilane (MPS),and aminopropyltri methoxysilane (APS).

[0043] In the exemplary embodiment, preparing the prehydrolyzed sol-gelmaterial involves mixing NMEOS and GLYMO monomers with a 15%stoichiometric amount of water. Enough HCI is added to the solution toproduce a solution whose PH in the range of about 2-5. The resultingsolution is stirred for about 15 minutes at a temperature of about 273Kelvin to start hydrolysis of the alkoxides. The hydrolysis reactionproduces primarily the amphiphilic organosilicate monomers 34 shown inFIG. 4. Next, the solution is heated to about 295 Kelvin and more wateris added. This causes further hydrolysis and produces the amphiphilicorganosilicate molecules 36 that are partially crosslinked as shown inFIG. 5. Stirring for about 1 hour completes the hydrolysis of alkoxidegroups and produces the prehydrolyzed sol-gel material used in abovestep 44.

[0044] Referring to FIG. 6, complete prehydrolysis produces additionalcrosslinking so that the final organosilicate precursors 37 of theprehydrolyzed sol-gel solution have higher molecular weights. Exemplaryweights are about 2 to about 200 times the weight of organosilicatemonomer 34 of FIG. 4. These partially crosslinked organosilicateprecursors 37 are still amphiphilic, because separate physical regions38, 39 of the precursor 37 have concentrations of hydrophobic (CH₃)moieties and concentrations of hydrophilic OCH₂(CHCH₂O) moieties,respectively.

[0045] Referring again to FIG. 3, method 40 includes mixing theprehydrolyzed solgel solution with the starting solution of PBu-b-PEO toform a mixture for casting, spin-coating, or dip-coating (step 46).After mixing, the mixture is typically stirred for about 2 hours to geta homogeneous solution. Then, the final mixture is either cast,spin-coated, or dip-coated on a selected substrate to produce a film ofa desired thickness (step 48).

[0046] The method 40 includes baking the cast, spin-coated, ordip-coated film to evaporate remaining solvent until the PBu-b-PEOtemplate molecules self-assemble into a phase with a mesoscopicstructure therein (step 50). The bake step maintains the film at atemperature slightly higher than the boiling point of the solvents untilthe solvent evaporates. Films produced by the casting, spin-coating, ordip-coating step 46 are typically thin enough so that bubbling can beavoided during the evaporation. Bubbling could otherwise, generatecracks in the film. Exemplary evaporate conditions for a 50/50 volume %solvent mixture of chloroform and tetrahydrofuran involve maintainingthe film at a temperature in the range of about 333 Kelvin to about 343Kelvin. At the desired PBu-b-PEO concentration, the PBu-b-PEO moleculesand the organosilicate precursors spontaneously condense to form one ofthe composites 2, 8, 14 of FIG. 1A, 1B, or 1C. The mesoscopic structureof the composite depends on the concentrations of PBu-b-PEO andorganosilicate precursors, the integers n and m characterizing the chainlengths of blocks in PBu-b-PEO, the molecular weights of theorganosilicate precursors, and the temperature.

[0047] The method 40 also includes baking the film at a highertemperature to cause crosslinking of the condensed organosilicateprecursors and produce an crosslinked organosilicate solid, i.e., asolid film (step 52). This higher temperature is about 103 Kelvin, andthe bake is continued for a period of about 45-60 minutes. The bakecures the composite by producing an organosilicate solid that is fullycrosslinked by siloxane crosslinks.

[0048] Since crosslinking causes the organosilicate precursors to shedalkoxide functional groups, the organosilicate precursors become lesshydrophilic and more hydrophobic as curing progresses. Nevertheless,curing does not cause shedding of the hydrophilic epoxide-type(CH₂(CHCH₂O) moieties or the hydrophobic CH₃ moieties under theconditions of the crosslinking bake. Curing also does not change theaffinities of these moieties for water. For this reason, theorganosilicate precursors remains amphiphilic during the bake and do notundergo a changes in their affinity for water during the cure. Avoidingchanges in affinities of the precursors for water avoids destroying thepreviously template-produced mesoscopic structure in the organosilicatecomposite.

[0049] In comparison, an organosilicate composite made by a sol-gelmaterial made by hydrolyzing only (CH₃)Si(OCH₂CH₃)₃ monomers will haveorganosilicate precursors that are hydrophilic before curing and becomehydrophobic, i.e.. as (OCH₂CH₃) moieties are shed during curing. In acomposite produced from such precursors, portions of organosilicateprecursors that were intermingled with or neighboring to hydrophilicregions of block polymers during template-induced formation of amesoscopic structure will become uncomfortable with their physicallocations as curing progresses. These organosilicate precursors moveduring curing and destroy the previously formed mesoscopic structure inthe organosilicate portion of the composite. A composite oforganosilicate precursors made by crosslinking the alkoxide(CH₃)Si(OCH₂CH₃)₃ alone will produce a cured organosilicate solidwithout mesoscopic structure, because the organosilicate precursorsbecome hydrophobic as their affinities for water change during the cure.

[0050] The method 40 also includes treating the crosslinked solid tochemically remove the block copolymer molecules that were previouslyused as a template for the mesoscopic structure (step 54). Possibletreatments include burning, ozonolysis. and O₂ plasma RIE. Afterremoving the block copolymer molecules or portions the remaining solidis porous. Sonie embodiments leave the pores in the solid empty inapplications, e.g., to make porous membranes for use as filters. Otherembodiments refill the pores with materials such as semiconductors,metals, and/or dyes for various uses.

[0051]FIG. 7 is a cross-sectional view of a planar waveguide 60 thatuses a porous organosilicate solid that was fabricated by method 40 ofFIG. 3. The waveguide 60 includes an optical core layer 62, an upperoptical cladding layer 64, and a substrate 66 that functions as a loweroptical cladding layer. The upper optical cladding layer 64 is a porousorganosilicate solid that was fabricated by method 40 of FIG. 3. Theporous nature of upper optical cladding layer 64 produces a very lowoptical refractive index therein. In the upper optical cladding layer64, exemplary refractive indexes potentially have low values in therange of about 1.1 to about 1.3 due to the porous nature of theorganosilicate solid. These refractive index values are lower than theapproximate values of 1.3-1.4 for refractive index that in obtainable byfluorine doping polymers. Such low refractive indexes aid to produce ahigh refractive index contrast between the upper optical cladding layer64 and the optical core layer 62 of the planar waveguide 60. Opticalwaveguides with high contrasts in refractive indexes between the opticalcore and cladding layers are known as a high delta waveguides. Highdelta waveguides are advantageous for some applications. The lowrefractive indexes in optical cladding layer 64 also enable using lowerrefractive indexes in optical core layer 62.

[0052] In the planar waveguide 60, the template-based fabricationprocess has concentrated hydrophobic moieties of organosilicateprecursors on the exterior of the optical cladding layer 64. Thepresence of such hydrophobic moieties enables the layer 64 to protectthe planar waveguide 60 from absorption of ambient water withoutadditional protective layers. Water absorption especially into theoptical core layer 62 could produce significant optical losses, e.g., atoptical telecommunication wavelengths of about 1.3 microns to about 1.6microns. The hydrophobicity of the upper optical cladding layer 64eliminates the need for additional waterproof coatings to protect theoptical core layer 62 from absorbing such damaging moisture.

[0053] Other embodiments of the invention will be apparent to those ofskill in the are in light of the specification, drawings, and claims ofthis application.

What we claim is:
 1. A method, comprising: providing a solution ofamphiphilic template molecules; mixing amphiphilic organosilicateprecursors into the solution to form a mixture; and evaporating solventfrom the mixture to produce an organosilicate composite with amesoscopic structure.
 2. The method of claim I, further comprising:curing the composite in a manner that crosslinks at least a portion ofthe organosilicate precursors.
 3. The method of claim 2, furthercomprising: forming a film of the mixture prior to completion of theevaporating.
 4. The method of claim 2, wherein the template moleculesare amphiphilic block copolymer molecules.
 5. The method of claim 4,wherein the amphiphilic organosilicate precursors remain amphiphilicduring the curing.
 6. The method of claim 5, wherein the crosslinkingreleases hydrophilic moieties from a portion of the organosilicateprecursors.
 7. The method of claim
 2. further comprising: performing achemical treatment that removes a portion of the template molecules fromthe cured composite.
 8. The method of claim 2, wherein hydrophobicmoieties bonded to the organosilicate precursors and hydrophilicmoieties bonded to the organosilicate precursors are concentrated inseparate physical regions of the cured composite.
 9. The method of claim1, wherein the mesoscopic structure includes a dispersion of amicro-structures of a type selected from a group consisting ofcylindrical micro-structures, lamellar micro-structures, gyroidmicro-structures, and spherical micro-structures.
 10. A apparatus,comprising: a solid that comprises an crosslinked collection ofamphiphilic organosilicate precursors; and wherein the amphiphilicorganosilicate precursors form a matrix with an array ofmicro-structures dispersed in the matrix.
 11. The apparatus of claim 10,wherein the micro-structures are voids or pores in the matrix.
 12. Theapparatus of claim 11, wherein the voids or pores are hydrophilic andportions of the matrix not adjacent to the voids or pores arehydrophobic.
 13. The apparatus of claim 11, wherein the solid isnon-wettable by water.
 14. The apparatus of claim 11, furthercomprising: a planar optical waveguide comprising an optical core layerand the solid; and wherein the solid forms an optical cladding layer forthe optical core layer.
 15. A method, comprising: forming a compositewith an internal structure by evaporating solvent from a solutioncomprising amphiphilic block copolymer molecules and amphiphilicorganosilicate precursors; and crosslinking a portion of theorganosilicate precursors of the composite to form an organosilicatesolid, and wherein the crosslinking conserves an amphiphilic nature ofat least a portion of the organosilicate precursors incorporated intothe solid.
 16. The method of claim 15, further comprising one ofcasting, dip-coating, and spin-coating a film of the solution on asubstrate prior to completion of the forming a composite.
 17. The methodof claim 15, wherein the crosslinking produces siloxane bonds betweenthe portion of the organosilicate precursors and causes the portion toshed alkoxide groups.
 18. The method of claim of claim 15, furthercomprising: chemically extracting block copolymer molecules from thesolid to create pores or voids in the solid.
 19. The method of claim 18,wherein the pores or voids are hydrophilic and portions of the matrixdistant from the pores or voids are hydrophobic.
 20. The method of claim15, wherein the internal structure includes a dispersion of one type ofmicro-structures in the composite, the type of microstructures beingselected from a group consisting of cylinders, lamellae, gyroids. andspheres.